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Ge-Te-As GLASSES AND METHOD OF PREPARATION Filed March 2, 1964 A. R. HILTON. JR,

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ALBERT RAY HILTON, JR.

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Sept. 26, 1967 A. R. HILTOIN, JR., ETAL. 3,343,972

Ge-Te-A; GLASSES AND METHOD OF PREPARATION Filed March 2, 1964 2 Sheets-Sheet 2 ,I-'.I -I I'I"'I 50 SAMPLE N I60 O E 30 SAMPLE N Z 20 N I60 GeAs Te REFRACTIVE INDEX-3.5

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ALBERT RAY HILTON, JR. CHARLIE EARL JONES,JR. MAURICE J. BRAU INVENTORS ATTORNEY United States Patent 3,343,972 Ge-Te-As GLASSES AND METHOD OF PREPARATION Albert Ray Hilton, Jr., Charlie Earl Jones, Jr., and Manrice J. Bran, Richardson, Tex., assignors to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Mar. 2, 1964, Ser. No. 348,642 6 Claims. (Cl. 106-47) ABSTRACT OF THE DISCLOSURE Disclosed are compositions of matter comprising germanium, arsenic, and tellurium many samples of which have been found to be glasses which transmit energy in the infrared region of the electromagnetic spectrum, and some samples of which have been found to be crystalline. Also disclosed are methods of compounding said glasses, and apparatus for measuring the softening points of said glasses.

This invention relates to amorphous compositions of matter. More particularly it relates to infrared transparent glasses and to a method of making same.

The invention disclosed herein appertains to germaniumarsenic-tellurium amorphous glass compositions which are transparent to the infrared region of the electromagnetic spectrum. Moreover, the invention provides compositions of matter having good transmission in the 1 to 25 micron wave length region of the electromagnetic spectrum.

The glasses of the invention may contain up to 20 (e.g., from greater than 0 up to but not including 20) atom percent germanium, 25 to 85 atom percent tellurium and 5 to 70 atom percent arsenic. The amorphous compositions of matter of the invention are in ternary form and may be made by forming a melt of the constituents and quenchcooling the melt from about 950 C. to 1000" C. to room temperature in air.

It is therefore an object of the invention to provide an amorphous composition of matter comprising in major proportion or consisting essentially of germanium, arsenic and tellurium.

Another object of the invention is to provide an amorphous composition of matter having a high transmission in the l to 25 micron wave length region of the electromagnetic spectrum.

A further object of the invention is to provide an amorphous composition of matter comprising in major proportion or consisting essentially of up to 20 atom percent germanium, 25 to 85 atom percent tellurium and 5 to 70 atom percent arsenic.

Another object of this invention is to provide a ternary germanium-arsenic-tellurium amorphous composition of matter having good transmission at high temperatures in the 1 to 25 micron wave length region of the electromagnetic spectrum.

A further object of the invention is to provide a method of making ternary amorphous compositions of matter having a transmission in the 1 to 25 micron region of the electromagnetic spectrum.

It is still a further object of the invention to provide a quench-freeze method of making germanium-arsenio tellurium amorphous compositions of matter having high softening points.

Still another object of the invention is to provide germanium-arsenic-tellurium amorphous compositions of matter exhibiting a high softening point and good transmission in the 1 to 25 micron region of the electromagnetic spectrum.

3,343,972 Patented Sept. 26, 1967 These and other objects, advantages and features of the invention will become more readily apparent from the following detailed description taken in conjunction with the appended claims and attached drawings wherein:

FIGURE 1 depicts a ternary diagram of the atomic percentages of the various germanium, arsenic and tellurium amorphous compositions of matter according to this invention, the crystalline com-positions being indi cated by triangles and the amorphous compositions being indicated by squares or circles;

FIGURE 2 illustrates a Soft-Point apparatus utilized in obtaining characteristic properties of the glass; and

FIGURE 3 is a graphical representation of percent transmission at room temperature of various wave lengths of the electromagnetic spectrum for various glass compositions according to this invention.

Referring to FIGURE 1, various compositions of germanium, arsenic and tellurium were compounded and evaluated to determine whether they were amorphous or crystalline. The general procedure for making the various compositions is described hereinafter.

Various atomic percents of germanium, tellurium and arsenic were chosen for each sample to be made. The appropriate amounts of the constituents were weighed and then placed in a previously cleaned quartz ampoule. An example of a suitable cleaning step for the ampoule is by etching 30 minutes in a 10% solution of concentrated hydrofluoric (48% HF) acid, rinsing in deionized water about 15 minutes, treating with aqua regia, rinsing in deionized water and then drying.

The total weight of each of the samples was between 5 and 15 grams. The constituents were placed in the cleaned tube and evacuated to about 10 torr and sealed. The sealed tubes were then placed in a furnace and gradually heated to a temperature of about 950 C. to 1000 C. and held at that temperature for about 15 to 36 hours to provide sufiicient time for the constituents to react completely with each other. The furnace was a rocking furnace which may be of any suitable design to provide agitation of the constituents so as to achieve maximum complete reaction thereof. The samples were then removed from the furnace and held in a vertical position in air for air quenching and allowed to cool to room temperature.

The sample compositions which failed to form amorphous glass by the air quench-cooling technique and were crystalline after quenching are presented in Table I, below, whereas the compositions which formed amorphous glass are presented in Table II below, with the Soft-Point results achieved for the glass. The reaction condition for the samples in Tables I and II below were the same. The samples were held at a temperature between 950 C. and 1000 C. for a period of about 15-36 hours.

TABLE I Composition, Composition, Atomic Percent Atomic Percent Sample No. Sample No.

Ge As Te TABLE II Composition, Atomic Percent Sample No. Softening Point in 0. Ge As Te *2 phases.

In FIGURE 1 the peripheral lines A and B generally circumscribe the amorphous compositions of germanium, arsenic and tellurium according to this invention. The samples which failed to form amorphous glass by the air quench cooling technique (listed in Table I) are plotted on FIGURE 1 by a black triangular dot and each identified by a sample number. The sample compositions forming amorphous glass listed in Table II are also plotted in FIGURE 1 within the areas generally circumscribed by lines A and B, and designated by both black circles and black square dots and each identified by a sample number. The amorphous samples indicated by black circular dots were discovered to show two distinct amorphous phases, indicating that an immiscible system exists in these composition regions.

Referring specifically to FIGURE 2, there is schematically illustrated apparatus suitable for use in determining the Soft-Point listed in Table II. The apparatus, generally referred to as 100, consists of a quartz tube 101 supported within a heating mantle 102 by mounting plate 103. The heating mantle 102 has a base plate 106 seated on an asbestos pad 104. The quartz tube 101 has an enlarged bore 107 which retains a boron nitride sample holder 108 having a hollow depression 109 therein. A sample slice 110 to be tested for Soft-Point is placed over the depression 109. A quartz rod 111 is supported within the quartz tube 101, resting against the surface of sample 110. To maintain the quartz rod in vertical alignment with respect to the quartz tube 101, a quartz guide 112 is provided. At the upper end of the quartz rod 111 a right angle bend is provided therein and the end of the quartz rod tapered to form a pointer 113. A scale 114 is provided to show movement of the quartz rod 111. The scale 114 is supported by means not illustrated in fixed relation to the sample slice 110. A thermocouple 115 is provided abutting the sample surface for measuring the temperature of sample 110.

In operation of the Soft-Point test apparatus 100, an amorphous glass sample 110 is placed in its proper position and heat is applied by the heating manifold 102. The temperature of the sample is slowly increased until the quartz rod 111, under the influence of its weight, deforms the sample 110, the amount of the deformation being indicated by the pointer 113 moving over the scale 114.

The room temperature transmission of various samples at various wave lengths of the electromagnetic spectrum is presented in Table HI below.

TABLE III.-INFRARED TRANSMISSION OF SOME Ge-AS-Te GLASSES In FIGURE 3, the percent transmission of the electromagnetic spectrum in the 1 to 25 micron wave length region is plotted for various of the glass samples contained in Table II, with an indication given as to index of refraction (N) and thickness of sample.

It should be undertsood that although most of the samples tested were essentially germanium, arsenic and tellurium, minor percentages of silicon, selenium, sulphur, antimony, phosphorous, bismuth, etc., may be used in the glass of the invention to provide variations in the softening point and transmission of the glass compositions.

Although only the air quench-cooling method has been described for making the amorphous compositions of matter of the invention, other methods could be used. Furthermore, the limits of composition for making amorphous material may be extended by more rapid quenching than provided by air quenching. Also, to achieve amorphous composition, the initial temperature for forming the melt may be extended several 100 degrees higher than described herein.

It should be appreciated that many other variations and changes to the invention will immediately suggest themselves to those skilled in the art and such variations and changes are deemed to be Within the purview and scope of the invention as defined in the appended claims.

What is claimed is:

1. Glass compositions comprising germanium, tellurium and arsenic, having compositions within the range of from greater than zero and up to but not including 20 atomic percent germanium, 25 to atomic percent tellurium and 5 to 70 atomic percent arsenic and lying within the regions circumscribed by lines A and B in the ternary diagram of FIGURE 1.

2. Glass compositions as circumscribed by line A in the ternary diagram of FIGURE 1.

3. Glass compositions as circumscribed by line B in the ternary diagram of FIGURE 1.

4. The method of making a glass composition for transmitting the 1 to 25 micron wave length portion of the electromagnetic spectrum comprising the steps of placing germanium, tellurium and arsenic having a composition within the boundaries circumscribed by lines A and B of FIGURE 1 into a reaction vessel, evacuating and sealing said vessel, agitating while heating said vessel to a temperature and for a period of time suflicient to form a. melt of said composition and to completely react said 3,343,972 5 6 germanium, tellurium and arsenic, and air quench-cool- References Cited ing said melt While still sealed in said vessel. UNITED STATES PATENTS s. thdfl' 4h "(it w is 33 5? 3 g w Sal empera re 3,241,009 3/1966 Dewald et a1. 106-47 6. The method of claim 5 wherein said period of time is about 15 to 36 hours 5 HELEN M. MCCARTHY, Przmary Exammer. 

1. GLASS COMPOSITIONS COMPRISING GERMANIUM, TELLURIUM AND ARSENIC, HAVING COMPOSITIONS WITHIN THE RANGE OF FROM GREATER THAN ZERO AND UP TO BUT NOT INCLUDING 20 ATOMIC PERCENT GERMANIUM, 25 TO 85 ATOMIC PERCENT TELLURIUM AND 5 TO 70 ATOMIC PERCENT ARSENIC AND LYING WITHIN THE REGIONS CIRCUMSCRIBED BY LINES A AND B IN THE TERNARY DIAGRAM OF FIGURE
 1. 4. THE METHOD OF MAKING A GLASS COMPOSITION FOR TRANSMITTING THE 1 TO 25 MICRON LENGTH PORTION OF THE ELECTROMAGNETIC SPECTRUM COMPRISING THE STEPS OF PLACING GERMANIUM, TELLURIUM AND ARSENIC HAVING A COMPOSITION WITHIN THE BOUNDARIES CIRCUMSCRIBED BY LINES A AND B OF 